Effect of Azo Dye Red 2G on Human Gamma Globulin using Multi-Spectroscopic and Docking Studies

Abstract

The study explored the binding interaction between human gamma globulin (HGG) and the synthetic azo dye red 2G (R2G) using spectroscopic techniques and molecular docking studies. The binding effects were identified through UV-visible, fluorescence and FT-IR spectroscopies. The quenching mechanism was found to be static, resulting in the formation of a stable bioconjugate, as determined by Stern-Volmer analysis. The binding distance between R2G and the tryptophan residue of HGG was studied using the Forster resonance energy transfer (FRET) theory. The study also found significant modification in the amide FTIR frequencies correlating to variation in the secondary α-helical structures of HGG at the HGG-R2G complex interface. The binding affinity scores of the protein HGG with the dye were determined using molecular docking. Biophysical techniques, such as turbidity measurements and field emission scanning electron microscopy (FESEM), were used to understand the mechanism of R2G-induced amyloid aggregation in HGG at pH 2. Additionally, the study investigated the potential cytotoxic effects of red 2G on human THP-1 monocytes via an MTT assay. The effects of food colorants on biological macromolecules were studied and it was found that a higher concentration of red 2G has toxic potential to human THP-1 monocytes.